The present invention relates generally to data storage system head sliders. More particularly, the present invention relates to a magnetoresistive (MR) proximity head slider having a recessed MR element (MRE) to minimize thermal asperities in the read back signal.
In magnetic disc drive data storage devices, digital data are written to and read from a thin layer of magnetizable material on a surface of one or more rotating discs. Write and read operations are performed through write and read transducers which are carried in a slider body. The slider and transducers are sometimes collectively referred to as a head, and typically a single head is associated with each disc surface. When the read transducer is a magnetoresistive (MR) type sensor, the combination of the slider and the transducer are frequently referred to as an MR head. The heads are selectively moved under the control of electronic circuitry to any one of a plurality of circular, concentric data tracks on the disc surface by an actuator device. Each slider body includes an air bearing surface (ABS). As the disc rotates, the disc drags air beneath the ABS, which develops a lifting force that causes the head to lift and fly above the disc surface.
In operation, the MRE of the head can come into contact with asperities on the surface of the disc. This is particularly true in proximity type heads where the inductive write transducer comes into frequent contact with the glide avalanche of the media. Potentially, this contact between the MRE and asperities can cause data written to a particular location on the disc to be lost. Immediately after contact with an asperity, the heat generated by the contact changes the resistive properties of the MR sensor. As a result, the corresponding signal read by the MR head is distorted by a voltage spike and subsequent decay, sometimes causing the data stored near the asperity to be unrecoverable. The voltage spike in the read back signal is frequently referred to as a "thermal asperity," while the defect on the disc is referred to as an "asperity". However, since one is indicative of the other, the two terms are frequently used interchangeably. Since a large number of thermal asperities appear in the read back signal from contact with the glide avalanche of the media, the concept of MR proximity which involves direct contact of the MRE with the media is not feasible with the existing MRE sensitivity to thermal asperities.